If we see a young, phenotypically female patient with an XY karyotype, it is of great importance to differentiate between the testicular feminization syndrome and gonadal dysgenesis. Patients with testicular feminization will always have normal testes, which are situated either in the ovarian fossa or in the inguinal canal. Patients with gonadal dysgenesis always have streak gonads. The risk of developing a malignancy in an abnormally located testis is very low, certainly before puberty, whereas the risk for dysgenetic gonads to develop a malignancy is high. Testes in patients with testicular feminization have an important endocrine function in puberty, whereas in gonadal dysgenesis patients they do not. For these reasons, in patients with testicular feminization, one should not remove the testes until the completion of puberty, whereas in patients with gonadal dysgenesis removal should be performed immediately upon recognition of the disorder.